package com.example.demo;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

@WebServlet("/UploadServlet")
public class UploadServlet extends HttpServlet {

    private static final long serialVersionUID = 1l;

    private static final String UPLOAD_DIRECTORY = "upload";
    private static final int MEMORY_THRESHOLD = 1024 * 1024 * 3;
    private static final int MAX_FILE_SIZE = 1024 * 1024 * 40;
    private static final int MAX_REQUEST_SIZE = 1024 * 1024 * 50;

    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            //检测是否为多媒体上传
        if(!ServletFileUpload.isMultipartContent(req)){
            PrintWriter writer= resp.getWriter();
            writer.println("Error  :表单必须包含 enctype=multipart/form-data");
            writer.flush();
            return;
        }

        DiskFileItemFactory factory=new DiskFileItemFactory();
        factory.setSizeThreshold(MEMORY_THRESHOLD);

        factory.setRepository(new File(System.getProperty("java.io.tmpdir")));

        ServletFileUpload upload=new ServletFileUpload(factory);

        upload.setFileSizeMax(MAX_FILE_SIZE);
        upload.setSizeMax(MAX_FILE_SIZE);
        upload.setHeaderEncoding("UTF-8");

        String uploadPath=req.getServletContext().getRealPath("./")+File.separator+UPLOAD_DIRECTORY;

        File uploadDir=new File(uploadPath);
        if(!uploadDir.exists()){
            uploadDir.mkdir();
        }

        try{
            List<FileItem> formItems=upload.parseRequest(req);
            if(formItems!=null&&formItems.size()>0){
                for(FileItem item:formItems){
                    if(!item.isFormField()){
                        String fileName=new File(item.getName()).getName();
                        String filePath=uploadPath+File.separator+fileName;
                        File storeFile=new File(filePath);
                        System.out.println(filePath);
                        item.write(storeFile);
                        req.setAttribute("message","文件上传成功");
                    }
                }
            }
        }catch (Exception e){
            req.setAttribute("message","Error   "+e.getMessage());
        }

        req.getServletContext().getRequestDispatcher("/message.jsp").forward(req,resp);

    }
}
